content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2014, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * ---------------
   * TimeSeries.java
   * ---------------
   * (C) Copyright 2001-2014, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   Bryan Scott;
   *                   Nick Guenther;
   *
   * Changes
   * -------
   * 11-Oct-2001 : Version 1 (DG);
   * 14-Nov-2001 : Added listener mechanism (DG);
   * 15-Nov-2001 : Updated argument checking and exceptions in add() method (DG);
   * 29-Nov-2001 : Added properties to describe the domain and range (DG);
   * 07-Dec-2001 : Renamed TimeSeries --> BasicTimeSeries (DG);
   * 01-Mar-2002 : Updated import statements (DG);
   * 28-Mar-2002 : Added a method add(TimePeriod, double) (DG);
   * 27-Aug-2002 : Changed return type of delete method to void (DG);
   * 04-Oct-2002 : Added itemCount and historyCount attributes, fixed errors
   *               reported by Checkstyle (DG);
   * 29-Oct-2002 : Added series change notification to addOrUpdate() method (DG);
   * 28-Jan-2003 : Changed name back to TimeSeries (DG);
   * 13-Mar-2003 : Moved to com.jrefinery.data.time package and implemented
   *               Serializable (DG);
   * 01-May-2003 : Updated equals() method (see bug report 727575) (DG);
   * 14-Aug-2003 : Added ageHistoryCountItems method (copied existing code for
   *               contents) made a method and added to addOrUpdate.  Made a
   *               public method to enable ageing against a specified time
   *               (eg now) as opposed to lastest time in series (BS);
   * 15-Oct-2003 : Added fix for setItemCount method - see bug report 804425.
   *               Modified exception message in add() method to be more
   *               informative (DG);
   * 13-Apr-2004 : Added clear() method (DG);
   * 21-May-2004 : Added an extra addOrUpdate() method (DG);
   * 15-Jun-2004 : Fixed NullPointerException in equals() method (DG);
   * 29-Nov-2004 : Fixed bug 1075255 (DG);
   * 17-Nov-2005 : Renamed historyCount --> maximumItemAge (DG);
   * 28-Nov-2005 : Changed maximumItemAge from int to long (DG);
   * 01-Dec-2005 : New add methods accept notify flag (DG);
   * ------------- JFREECHART 1.0.x ---------------------------------------------
   * 24-May-2006 : Improved error handling in createCopy() methods (DG);
   * 01-Sep-2006 : Fixed bugs in removeAgedItems() methods - see bug report
   *               1550045 (DG);
   * 22-Mar-2007 : Simplified getDataItem(RegularTimePeriod) - see patch 1685500
   *               by Nick Guenther (DG);
   * 31-Oct-2007 : Implemented faster hashCode() (DG);
   * 21-Nov-2007 : Fixed clone() method (bug 1832432) (DG);
   * 10-Jan-2008 : Fixed createCopy(RegularTimePeriod, RegularTimePeriod) (bug
   *               1864222) (DG);
   * 13-Jan-2009 : Fixed constructors so that timePeriodClass doesn't need to
   *               be specified in advance (DG);
   * 26-May-2009 : Added cache for minY and maxY values (DG);
   * 09-Jun-2009 : Ensure that TimeSeriesDataItem objects used in underlying
   *               storage are cloned to keep series isolated from external
   *               changes (DG);
   * 10-Jun-2009 : Added addOrUpdate(TimeSeriesDataItem) method (DG);
   * 31-Aug-2009 : Clear minY and maxY cache values in createCopy (DG);
   * 03-Dec-2011 : Fixed bug 3446965 which affects the y-range calculation for
   *               the series (DG);
   * 16-Jun-2012 : Removed JCommon dependencies (DG);
   *
   */
  
  package org.jfree.data.time;
  
  import java.io.Serializable;
  import java.util.Calendar;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Date;
  import java.util.List;
  import java.util.Locale;
  import java.util.TimeZone;
  
  import org.jfree.chart.util.ObjectUtilities;
  import org.jfree.chart.util.ParamChecks;
  import org.jfree.data.Range;
  import org.jfree.data.general.Series;
  import org.jfree.data.general.SeriesException;
  
  /**
   * Represents a sequence of zero or more data items in the form (period, value)
   * where 'period' is some instance of a subclass of {@link RegularTimePeriod}.
   * The time series will ensure that (a) all data items have the same type of
   * period (for example, {@link Day}) and (b) that each period appears at
   * most one time in the series.
   */
  public class TimeSeries extends Series implements Cloneable, Serializable {
  
      /** For serialization. */
      private static final long serialVersionUID = -5032960206869675528L;
  
      /** Default value for the domain description. */
      protected static final String DEFAULT_DOMAIN_DESCRIPTION = "Time";
  
      /** Default value for the range description. */
      protected static final String DEFAULT_RANGE_DESCRIPTION = "Value";
  
      /** A description of the domain. */
      private String domain;
  
      /** A description of the range. */
      private String range;
  
      /** The type of period for the data. */
      protected Class<? extends TimePeriod> timePeriodClass;
  
      /** The list of data items in the series. */
      protected List<TimeSeriesDataItem> data;
  
      /** The maximum number of items for the series. */
      private int maximumItemCount;
  
      /**
       * The maximum age of items for the series, specified as a number of
       * time periods.
       */
      private long maximumItemAge;
  
      /**
       * The minimum y-value in the series.
       *
       * @since 1.0.14
       */
      private double minY;
  
      /**
       * The maximum y-value in the series.
       *
       * @since 1.0.14
       */
      private double maxY;
  
      /**
       * Creates a new (empty) time series.  By default, a daily time series is
       * created.  Use one of the other constructors if you require a different
       * time period.
       *
       * @param name  the series name (<code>null</code> not permitted).
       */
      public TimeSeries(Comparable name) {
          this(name, DEFAULT_DOMAIN_DESCRIPTION, DEFAULT_RANGE_DESCRIPTION);
      }
  
      /**
       * Creates a new time series that contains no data.
       * <P>
       * Descriptions can be specified for the domain and range.  One situation
       * where this is helpful is when generating a chart for the time series -
       * axis labels can be taken from the domain and range description.
       *
       * @param name  the name of the series (<code>null</code> not permitted).
       * @param domain  the domain description (<code>null</code> permitted).
       * @param range  the range description (<code>null</code> permitted).
       *
       * @since 1.0.13
       */
      public TimeSeries(Comparable name, String domain, String range) {
          super(name);
          this.domain = domain;
          this.range = range;
          this.timePeriodClass = null;
          this.data = new java.util.ArrayList<TimeSeriesDataItem>();
          this.maximumItemCount = Integer.MAX_VALUE;
          this.maximumItemAge = Long.MAX_VALUE;
          this.minY = Double.NaN;
          this.maxY = Double.NaN;
      }
  
      /**
       * Returns the domain description.
       *
       * @return The domain description (possibly <code>null</code>).
       *
       * @see #setDomainDescription(String)
       */
      public String getDomainDescription() {
          return this.domain;
      }
  
      /**
       * Sets the domain description and sends a <code>PropertyChangeEvent</code>
       * (with the property name <code>Domain</code>) to all registered
       * property change listeners.
       *
       * @param description  the description (<code>null</code> permitted).
       *
       * @see #getDomainDescription()
       */
      public void setDomainDescription(String description) {
          String old = this.domain;
          this.domain = description;
          firePropertyChange("Domain", old, description);
      }
  
      /**
       * Returns the range description.
       *
       * @return The range description (possibly <code>null</code>).
       *
       * @see #setRangeDescription(String)
       */
      public String getRangeDescription() {
          return this.range;
      }
  
      /**
       * Sets the range description and sends a <code>PropertyChangeEvent</code>
       * (with the property name <code>Range</code>) to all registered listeners.
       *
       * @param description  the description (<code>null</code> permitted).
       *
       * @see #getRangeDescription()
       */
      public void setRangeDescription(String description) {
          String old = this.range;
          this.range = description;
          firePropertyChange("Range", old, description);
      }
  
      /**
       * Returns the number of items in the series.
       *
       * @return The item count.
       */
      @Override
      public int getItemCount() {
          return this.data.size();
      }
  
      /**
       * Returns the list of data items for the series (the list contains
       * {@link TimeSeriesDataItem} objects and is unmodifiable).
       *
       * @return The list of data items.
       */
      public List<TimeSeriesDataItem> getItems() {
          // FIXME: perhaps we should clone the data list
          return Collections.unmodifiableList(this.data);
      }
  
      /**
       * Returns the maximum number of items that will be retained in the series.
       * The default value is <code>Integer.MAX_VALUE</code>.
       *
       * @return The maximum item count.
       *
       * @see #setMaximumItemCount(int)
       */
      public int getMaximumItemCount() {
          return this.maximumItemCount;
      }
  
      /**
       * Sets the maximum number of items that will be retained in the series.
       * If you add a new item to the series such that the number of items will
       * exceed the maximum item count, then the FIRST element in the series is
       * automatically removed, ensuring that the maximum item count is not
       * exceeded.
       *
       * @param maximum  the maximum (requires >= 0).
       *
       * @see #getMaximumItemCount()
       */
      public void setMaximumItemCount(int maximum) {
          if (maximum < 0) {
              throw new IllegalArgumentException("Negative 'maximum' argument.");
          }
          this.maximumItemCount = maximum;
          int count = this.data.size();
          if (count > maximum) {
              delete(0, count - maximum - 1);
          }
      }
  
      /**
       * Returns the maximum item age (in time periods) for the series.
       *
       * @return The maximum item age.
       *
       * @see #setMaximumItemAge(long)
       */
      public long getMaximumItemAge() {
          return this.maximumItemAge;
      }
  
      /**
       * Sets the number of time units in the 'history' for the series.  This
       * provides one mechanism for automatically dropping old data from the
       * time series. For example, if a series contains daily data, you might set
       * the history count to 30.  Then, when you add a new data item, all data
       * items more than 30 days older than the latest value are automatically
       * dropped from the series.
       *
       * @param periods  the number of time periods.
       *
       * @see #getMaximumItemAge()
       */
      public void setMaximumItemAge(long periods) {
          if (periods < 0) {
              throw new IllegalArgumentException("Negative 'periods' argument.");
          }
          this.maximumItemAge = periods;
          removeAgedItems(true);  // remove old items and notify if necessary
      }
  
      /**
       * Returns the range of y-values in the time series.  Any <code>null</code> 
       * data values in the series will be ignored (except for the special case 
       * where all data values are <code>null</code>, in which case the return 
       * value is <code>Range(Double.NaN, Double.NaN)</code>).  If the time 
       * series contains no items, this method will return <code>null</code>.
       * 
       * @return The range of y-values in the time series (possibly 
       *     <code>null</code>).
       * 
       * @since 1.0.18
       */
      public Range findValueRange() {
          if (this.data.isEmpty()) {
              return null;
          }
          return new Range(this.minY, this.maxY);
      }
      
      /**
       * Returns the range of y-values in the time series that fall within 
       * the specified range of x-values.  This is equivalent to
       * <code>findValueRange(xRange, TimePeriodAnchor.MIDDLE, timeZone)</code>.
       * 
       * @param xRange  the subrange of x-values (<code>null</code> not 
       *     permitted).
       * @param timeZone  the time zone used to convert x-values to time periods
       *     (<code>null</code> not permitted).
       * 
       * @return The range. 
       * 
       * @since 1.0.18
       */
      public Range findValueRange(Range xRange, TimeZone timeZone) {
          return findValueRange(xRange, TimePeriodAnchor.MIDDLE, timeZone);
      }
      
      /**
       * Finds the range of y-values that fall within the specified range of
       * x-values (where the x-values are interpreted as milliseconds since the
       * epoch and converted to time periods using the specified timezone).
       * 
       * @param xRange  the subset of x-values to use (<coded>null</code> not
       *     permitted).
       * @param xAnchor  the anchor point for the x-values (<code>null</code>
       *     not permitted).
       * @param zone  the time zone (<code>null</code> not permitted).
       * 
       * @return The range of y-values.
       * 
       * @since 1.0.18
       */
      public Range findValueRange(Range xRange, TimePeriodAnchor xAnchor, 
              TimeZone zone) {
          ParamChecks.nullNotPermitted(xRange, "xRange");
          ParamChecks.nullNotPermitted(xAnchor, "xAnchor");
          ParamChecks.nullNotPermitted(zone, "zone");
          if (this.data.isEmpty()) {
              return null;
          }
          Calendar calendar = Calendar.getInstance(zone);
          // since the items are ordered, we could be more clever here and avoid
          // iterating over all the data
          double lowY = Double.POSITIVE_INFINITY;
          double highY = Double.NEGATIVE_INFINITY;
          for (TimeSeriesDataItem item : this.data) {
              long millis = item.getPeriod().getMillisecond(xAnchor, calendar);
              if (xRange.contains(millis)) {
                  Number n = item.getValue();
                  if (n != null) {
                      double v = n.doubleValue();
                      lowY = Math.min(lowY, v);
                      highY = Math.max(highY, v);
                  }
              }
          }
          if (Double.isInfinite(lowY) && Double.isInfinite(highY)) {
              if (lowY < highY) {
                  return new Range(lowY, highY);
              } else {
                  return new Range(Double.NaN, Double.NaN);
              }
          }
          return new Range(lowY, highY);
      }
  
      /**
       * Returns the smallest y-value in the series, ignoring any 
       * <code>null</code> and <code>Double.NaN</code> values.  This method 
       * returns <code>Double.NaN</code> if there is no smallest y-value (for 
       * example, when the series is empty).
       *
       * @return The smallest y-value.
       *
       * @see #getMaxY()
       *
       * @since 1.0.14
       */
      public double getMinY() {
          return this.minY;
      }
  
      /**
       * Returns the largest y-value in the series, ignoring any 
       * <code>null</code> and <code>Double.NaN</code> values.  This method 
       * returns <code>Double.NaN</code> if there is no largest y-value
       * (for example, when the series is empty).
       *
       * @return The largest y-value.
       *
       * @see #getMinY()
       *
       * @since 1.0.14
       */
      public double getMaxY() {
          return this.maxY;
      }
  
      /**
       * Returns the time period class for this series.
       * <p>
       * Only one time period class can be used within a single series (enforced).
       * If you add a data item with a {@link Year} for the time period, then all
       * subsequent data items must also have a {@link Year} for the time period.
       *
       * @return The time period class (may be <code>null</code> but only for
       *     an empty series).
       */
      public Class getTimePeriodClass() {
          return this.timePeriodClass;
      }
  
      /**
       * Returns a data item from the dataset.  Note that the returned object
       * is a clone of the item in the series, so modifying it will have no
       * effect on the data series.
       *
       * @param index  the item index.
       *
       * @return The data item.
       */
      public TimeSeriesDataItem getDataItem(int index) {
          TimeSeriesDataItem item = this.data.get(index);
          return (TimeSeriesDataItem) item.clone();
      }
  
      /**
       * Returns the data item for a specific period.  Note that the returned
       * object is a clone of the item in the series, so modifying it will have
       * no effect on the data series.
       *
       * @param period  the period of interest (<code>null</code> not allowed).
       *
       * @return The data item matching the specified period (or
       *         <code>null</code> if there is no match).
       *
       * @see #getDataItem(int)
       */
      public TimeSeriesDataItem getDataItem(RegularTimePeriod period) {
          int index = getIndex(period);
          if (index >= 0) {
              return getDataItem(index);
          }
          return null;
      }
  
      /**
       * Returns a data item for the series.  This method returns the object
       * that is used for the underlying storage - you should not modify the
       * contents of the returned value unless you know what you are doing.
       *
       * @param index  the item index (zero-based).
       *
       * @return The data item.
       *
       * @see #getDataItem(int)
       *
       * @since 1.0.14
       */
      TimeSeriesDataItem getRawDataItem(int index) {
          return this.data.get(index);
      }
  
      /**
       * Returns a data item for the series.  This method returns the object
       * that is used for the underlying storage - you should not modify the
       * contents of the returned value unless you know what you are doing.
       *
       * @param period  the item index (zero-based).
       *
       * @return The data item.
       *
       * @see #getDataItem(RegularTimePeriod)
       *
       * @since 1.0.14
       */
      TimeSeriesDataItem getRawDataItem(RegularTimePeriod period) {
          int index = getIndex(period);
          if (index >= 0) {
              return this.data.get(index);
          }
          return null;
      }
  
      /**
       * Returns the time period at the specified index.
       *
       * @param index  the index of the data item.
       *
       * @return The time period.
       */
      public RegularTimePeriod getTimePeriod(int index) {
          return getRawDataItem(index).getPeriod();
      }
  
      /**
       * Returns a time period that would be the next in sequence on the end of
       * the time series.
       *
       * @return The next time period.
       */
      public RegularTimePeriod getNextTimePeriod() {
          RegularTimePeriod last = getTimePeriod(getItemCount() - 1);
          return last.next();
      }
  
      /**
       * Returns a collection of all the time periods in the time series.
       *
       * @return A collection of all the time periods.
       */
      public Collection<RegularTimePeriod> getTimePeriods() {
          Collection<RegularTimePeriod> result = new java.util.ArrayList<RegularTimePeriod>();
          for (int i = 0; i < getItemCount(); i++) {
              result.add(getTimePeriod(i));
          }
          return result;
      }
  
      /**
       * Returns a collection of time periods in the specified series, but not in
       * this series, and therefore unique to the specified series.
       *
       * @param series  the series to check against this one.
       *
       * @return The unique time periods.
       */
      public Collection<RegularTimePeriod> getTimePeriodsUniqueToOtherSeries(TimeSeries series) {
          Collection<RegularTimePeriod> result = new java.util.ArrayList<RegularTimePeriod>();
          for (int i = 0; i < series.getItemCount(); i++) {
              RegularTimePeriod period = series.getTimePeriod(i);
              int index = getIndex(period);
              if (index < 0) {
                  result.add(period);
              }
          }
          return result;
      }
  
      /**
       * Returns the index for the item (if any) that corresponds to a time
       * period.
       *
       * @param period  the time period (<code>null</code> not permitted).
       *
       * @return The index.
       */
      public int getIndex(RegularTimePeriod period) {
          ParamChecks.nullNotPermitted(period, "period");
          TimeSeriesDataItem dummy = new TimeSeriesDataItem(
                period, Integer.MIN_VALUE);
          return Collections.binarySearch(this.data, dummy);
      }
  
      /**
       * Returns the value at the specified index.
       *
       * @param index  index of a value.
       *
       * @return The value (possibly <code>null</code>).
       */
      public Number getValue(int index) {
          return getRawDataItem(index).getValue();
      }
  
      /**
       * Returns the value for a time period.  If there is no data item with the
       * specified period, this method will return <code>null</code>.
       *
       * @param period  time period (<code>null</code> not permitted).
       *
       * @return The value (possibly <code>null</code>).
       */
      public Number getValue(RegularTimePeriod period) {
          int index = getIndex(period);
          if (index >= 0) {
              return getValue(index);
          }
          return null;
      }
  
      /**
       * Adds a data item to the series and sends a {@link SeriesChangeEvent} to
       * all registered listeners.
       *
       * @param item  the (timeperiod, value) pair (<code>null</code> not
       *              permitted).
       */
      public void add(TimeSeriesDataItem item) {
          add(item, true);
      }
  
      /**
       * Adds a data item to the series and sends a {@link SeriesChangeEvent} to
       * all registered listeners.
       *
       * @param item  the (timeperiod, value) pair (<code>null</code> not
       *              permitted).
       * @param notify  notify listeners?
       */
      public void add(TimeSeriesDataItem item, boolean notify) {
          ParamChecks.nullNotPermitted(item, "item");
          item = (TimeSeriesDataItem) item.clone();
          Class<? extends TimePeriod> c = item.getPeriod().getClass();
          if (this.timePeriodClass == null) {
              this.timePeriodClass = c;
          }
          else if (!this.timePeriodClass.equals(c)) {
              StringBuilder b = new StringBuilder();
              b.append("You are trying to add data where the time period class ");
              b.append("is ");
              b.append(item.getPeriod().getClass().getName());
              b.append(", but the TimeSeries is expecting an instance of ");
              b.append(this.timePeriodClass.getName());
              b.append(".");
              throw new SeriesException(b.toString());
          }
  
          // make the change (if it's not a duplicate time period)...
          boolean added;
          int count = getItemCount();
          if (count == 0) {
              this.data.add(item);
              added = true;
          }
          else {
              RegularTimePeriod last = getTimePeriod(getItemCount() - 1);
              if (item.getPeriod().compareTo(last) > 0) {
                  this.data.add(item);
                  added = true;
              }
              else {
                  int index = Collections.binarySearch(this.data, item);
                  if (index < 0) {
                      this.data.add(-index - 1, item);
                      added = true;
                  }
                  else {
                      StringBuilder b = new StringBuilder();
                      b.append("You are attempting to add an observation for ");
                      b.append("the time period ");
                      b.append(item.getPeriod().toString());
                      b.append(" but the series already contains an observation");
                      b.append(" for that time period. Duplicates are not ");
                      b.append("permitted.  Try using the addOrUpdate() method.");
                      throw new SeriesException(b.toString());
                  }
              }
          }
          if (added) {
              updateBoundsForAddedItem(item);
              // check if this addition will exceed the maximum item count...
              if (getItemCount() > this.maximumItemCount) {
                  TimeSeriesDataItem d = this.data.remove(0);
                  updateBoundsForRemovedItem(d);
              }
  
              removeAgedItems(false);  // remove old items if necessary, but
                                       // don't notify anyone, because that
                                       // happens next anyway...
              if (notify) {
                  fireSeriesChanged();
              }
          }
  
      }
  
      /**
       * Adds a new data item to the series and sends a {@link SeriesChangeEvent}
       * to all registered listeners.
       *
       * @param period  the time period (<code>null</code> not permitted).
       * @param value  the value.
       */
      public void add(RegularTimePeriod period, double value) {
          // defer argument checking...
          add(period, value, true);
      }
  
      /**
       * Adds a new data item to the series and sends a {@link SeriesChangeEvent}
       * to all registered listeners.
       *
       * @param period  the time period (<code>null</code> not permitted).
       * @param value  the value.
       * @param notify  notify listeners?
       */
      public void add(RegularTimePeriod period, double value, boolean notify) {
          // defer argument checking...
          TimeSeriesDataItem item = new TimeSeriesDataItem(period, value);
          add(item, notify);
      }
  
      /**
       * Adds a new data item to the series and sends
       * a {@link org.jfree.data.general.SeriesChangeEvent} to all registered
       * listeners.
       *
       * @param period  the time period (<code>null</code> not permitted).
       * @param value  the value (<code>null</code> permitted).
       */
      public void add(RegularTimePeriod period, Number value) {
          // defer argument checking...
          add(period, value, true);
      }
  
      /**
       * Adds a new data item to the series and sends a {@link SeriesChangeEvent}
       * to all registered listeners.
       *
       * @param period  the time period (<code>null</code> not permitted).
       * @param value  the value (<code>null</code> permitted).
       * @param notify  notify listeners?
       */
      public void add(RegularTimePeriod period, Number value, boolean notify) {
          // defer argument checking...
          TimeSeriesDataItem item = new TimeSeriesDataItem(period, value);
          add(item, notify);
      }
  
      /**
       * Updates (changes) the value for a time period.  Throws a
       * {@link SeriesException} if the period does not exist.
       *
       * @param period  the period (<code>null</code> not permitted).
       * @param value  the value.
       *
       * @since 1.0.14
       */
      public void update(RegularTimePeriod period, double value) {
        update(period, Double.valueOf(value));
      }
  
      /**
       * Updates (changes) the value for a time period.  Throws a
       * {@link SeriesException} if the period does not exist.
       *
       * @param period  the period (<code>null</code> not permitted).
       * @param value  the value (<code>null</code> permitted).
       */
      public void update(RegularTimePeriod period, Number value) {
          TimeSeriesDataItem temp = new TimeSeriesDataItem(period, value);
          int index = Collections.binarySearch(this.data, temp);
          if (index < 0) {
              throw new SeriesException("There is no existing value for the "
                      + "specified 'period'.");
          }
          update(index, value);
      }
  
      /**
       * Updates (changes) the value of a data item.
       *
       * @param index  the index of the data item.
       * @param value  the new value (<code>null</code> permitted).
       */
      public void update(int index, Number value) {
          TimeSeriesDataItem item = this.data.get(index);
          boolean iterate = false;
          Number oldYN = item.getValue();
          if (oldYN != null) {
              double oldY = oldYN.doubleValue();
              if (!Double.isNaN(oldY)) {
                  iterate = oldY <= this.minY || oldY >= this.maxY;
              }
          }
          item.setValue(value);
          if (iterate) {
              updateMinMaxYByIteration();
          }
          else if (value != null) {
              double yy = value.doubleValue();
              this.minY = minIgnoreNaN(this.minY, yy);
              this.maxY = maxIgnoreNaN(this.maxY, yy);
          }
          fireSeriesChanged();
      }
  
      /**
       * Adds or updates data from one series to another.  Returns another series
       * containing the values that were overwritten.
       *
       * @param series  the series to merge with this.
       *
       * @return A series containing the values that were overwritten.
       */
      public TimeSeries addAndOrUpdate(TimeSeries series) {
          TimeSeries overwritten = new TimeSeries("Overwritten values from: "
                  + getKey());
          for (int i = 0; i < series.getItemCount(); i++) {
              TimeSeriesDataItem item = series.getRawDataItem(i);
              TimeSeriesDataItem oldItem = addOrUpdate(item.getPeriod(),
                      item.getValue());
              if (oldItem != null) {
                  overwritten.add(oldItem);
              }
          }
          return overwritten;
      }
  
      /**
       * Adds or updates an item in the times series and sends a
       * {@link SeriesChangeEvent} to all registered listeners.
       *
       * @param period  the time period to add/update (<code>null</code> not
       *                permitted).
       * @param value  the new value.
       *
       * @return A copy of the overwritten data item, or <code>null</code> if no
       *         item was overwritten.
       */
      public TimeSeriesDataItem addOrUpdate(RegularTimePeriod period,
                                            double value) {
          return addOrUpdate(period, Double.valueOf(value));
      }
  
      /**
       * Adds or updates an item in the times series and sends a
       * {@link SeriesChangeEvent} to all registered listeners.
       *
       * @param period  the time period to add/update (<code>null</code> not
       *                permitted).
       * @param value  the new value (<code>null</code> permitted).
       *
       * @return A copy of the overwritten data item, or <code>null</code> if no
       *         item was overwritten.
       */
      public TimeSeriesDataItem addOrUpdate(RegularTimePeriod period,
                                            Number value) {
          return addOrUpdate(new TimeSeriesDataItem(period, value));
      }
  
      /**
       * Adds or updates an item in the times series and sends a
       * {@link SeriesChangeEvent} to all registered listeners.
       *
       * @param item  the data item (<code>null</code> not permitted).
       *
       * @return A copy of the overwritten data item, or <code>null</code> if no
       *         item was overwritten.
       *
       * @since 1.0.14
       */
      public TimeSeriesDataItem addOrUpdate(TimeSeriesDataItem item) {
  
          ParamChecks.nullNotPermitted(item, "item");
          Class<? extends TimePeriod> periodClass = item.getPeriod().getClass();
          if (this.timePeriodClass == null) {
              this.timePeriodClass = periodClass;
          }
          else if (!this.timePeriodClass.equals(periodClass)) {
              String msg = "You are trying to add data where the time "
                      + "period class is " + periodClass.getName()
                      + ", but the TimeSeries is expecting an instance of "
                      + this.timePeriodClass.getName() + ".";
              throw new SeriesException(msg);
          }
          TimeSeriesDataItem overwritten = null;
          int index = Collections.binarySearch(this.data, item);
          if (index >= 0) {
              TimeSeriesDataItem existing
                      = this.data.get(index);
              overwritten = (TimeSeriesDataItem) existing.clone();
              // figure out if we need to iterate through all the y-values
              // to find the revised minY / maxY
              boolean iterate = false;
              Number oldYN = existing.getValue();
              double oldY = oldYN != null ? oldYN.doubleValue() : Double.NaN;
              if (!Double.isNaN(oldY)) {
                  iterate = oldY <= this.minY || oldY >= this.maxY;
              }
              existing.setValue(item.getValue());
              if (iterate) {
                  updateMinMaxYByIteration();
              }
              else if (item.getValue() != null) {
                  double yy = item.getValue().doubleValue();
                  this.minY = minIgnoreNaN(this.minY, yy);
                  this.maxY = maxIgnoreNaN(this.maxY, yy);
              }
          }
          else {
              item = (TimeSeriesDataItem) item.clone();
              this.data.add(-index - 1, item);
              updateBoundsForAddedItem(item);
  
              // check if this addition will exceed the maximum item count...
              if (getItemCount() > this.maximumItemCount) {
                  TimeSeriesDataItem d = this.data.remove(0);
                  updateBoundsForRemovedItem(d);
              }
          }
          removeAgedItems(false);  // remove old items if necessary, but
                                   // don't notify anyone, because that
                                   // happens next anyway...
          fireSeriesChanged();
          return overwritten;
  
      }
  
      /**
       * Age items in the series.  Ensure that the timespan from the youngest to
       * the oldest record in the series does not exceed maximumItemAge time
       * periods.  Oldest items will be removed if required.
       *
       * @param notify  controls whether or not a {@link SeriesChangeEvent} is
       *                sent to registered listeners IF any items are removed.
       */
      public void removeAgedItems(boolean notify) {
          // check if there are any values earlier than specified by the history
          // count...
          if (getItemCount() > 1) {
              long latest = getTimePeriod(getItemCount() - 1).getSerialIndex();
              boolean removed = false;
              while ((latest - getTimePeriod(0).getSerialIndex())
                      > this.maximumItemAge) {
                  this.data.remove(0);
                  removed = true;
              }
              if (removed) {
                  updateMinMaxYByIteration();
                  if (notify) {
                      fireSeriesChanged();
                  }
              }
          }
      }
  
      /**
       * Age items in the series.  Ensure that the timespan from the supplied
       * time to the oldest record in the series does not exceed history count.
       * oldest items will be removed if required.
       *
       * @param latest  the time to be compared against when aging data
       *     (specified in milliseconds).
       * @param notify  controls whether or not a {@link SeriesChangeEvent} is
       *                sent to registered listeners IF any items are removed.
       */
      public void removeAgedItems(long latest, boolean notify) {
          if (this.data.isEmpty()) {
              return;  // nothing to do
          }
          // find the serial index of the period specified by 'latest'
          RegularTimePeriod newest = RegularTimePeriod.createInstance(
                  this.timePeriodClass, new Date(latest), TimeZone.getDefault(),
                  Locale.getDefault());
          long index = newest.getSerialIndex();
  
          // check if there are any values earlier than specified by the history
          // count...
          boolean removed = false;
          while (getItemCount() > 0 && (index
                  - getTimePeriod(0).getSerialIndex()) > this.maximumItemAge) {
              this.data.remove(0);
              removed = true;
          }
          if (removed) {
              updateMinMaxYByIteration();
              if (notify) {
                  fireSeriesChanged();
              }
          }
      }
  
      /**
       * Removes all data items from the series and sends a
       * {@link SeriesChangeEvent} to all registered listeners.
       */
      public void clear() {
          if (this.data.size() > 0) {
              this.data.clear();
              this.timePeriodClass = null;
              this.minY = Double.NaN;
              this.maxY = Double.NaN;
              fireSeriesChanged();
          }
      }
  
      /**
       * Deletes the data item for the given time period and sends a
       * {@link SeriesChangeEvent} to all registered listeners.  If there is no
       * item with the specified time period, this method does nothing.
       *
       * @param period  the period of the item to delete (<code>null</code> not
       *                permitted).
       */
      public void delete(RegularTimePeriod period) {
          int index = getIndex(period);
          if (index >= 0) {
              TimeSeriesDataItem item = this.data.remove(
                      index);
              updateBoundsForRemovedItem(item);
              if (this.data.isEmpty()) {
                  this.timePeriodClass = null;
              }
              fireSeriesChanged();
          }
      }
  
      /**
       * Deletes data from start until end index (end inclusive).
       *
       * @param start  the index of the first period to delete.
       * @param end  the index of the last period to delete.
       */
      public void delete(int start, int end) {
          delete(start, end, true);
      }
  
      /**
       * Deletes data from start until end index (end inclusive).
       *
       * @param start  the index of the first period to delete.
       * @param end  the index of the last period to delete.
       * @param notify  notify listeners?
       *
       * @since 1.0.14
       */
      public void delete(int start, int end, boolean notify) {
          if (end < start) {
              throw new IllegalArgumentException("Requires start <= end.");
          }
          for (int i = 0; i <= (end - start); i++) {
              this.data.remove(start);
          }
          updateMinMaxYByIteration();
          if (this.data.isEmpty()) {
              this.timePeriodClass = null;
          }
          if (notify) {
              fireSeriesChanged();
          }
      }
  
      /**
       * Returns a clone of the time series.
       * <P>
       * Notes:
       * <ul>
       *   <li>no need to clone the domain and range descriptions, since String
       *     object is immutable;</li>
       *   <li>we pass over to the more general method clone(start, end).</li>
       * </ul>
       *
       * @return A clone of the time series.
       *
       * @throws CloneNotSupportedException not thrown by this class, but
       *         subclasses may differ.
       */
      @Override
      public Object clone() throws CloneNotSupportedException {
          TimeSeries clone = (TimeSeries) super.clone();
          clone.data = ObjectUtilities.deepClone(this.data);
          return clone;
      }
  
      /**
       * Creates a new timeseries by copying a subset of the data in this time
       * series.
       *
       * @param start  the index of the first time period to copy.
       * @param end  the index of the last time period to copy.
       *
       * @return A series containing a copy of this times series from start until
       *         end.
       *
       * @throws CloneNotSupportedException if there is a cloning problem.
       */
      public TimeSeries createCopy(int start, int end)
              throws CloneNotSupportedException {
          if (start < 0) {
              throw new IllegalArgumentException("Requires start >= 0.");
          }
          if (end < start) {
              throw new IllegalArgumentException("Requires start <= end.");
          }
          TimeSeries copy = (TimeSeries) super.clone();
          copy.minY = Double.NaN;
          copy.maxY = Double.NaN;
          copy.data = new java.util.ArrayList<TimeSeriesDataItem>();
          if (this.data.size() > 0) {
              for (int index = start; index <= end; index++) {
                  TimeSeriesDataItem item
                          = this.data.get(index);
                  TimeSeriesDataItem clone = (TimeSeriesDataItem) item.clone();
                  try {
                      copy.add(clone);
                  }
                  catch (SeriesException e) {
                       throw new RuntimeException("Could not add cloned item to series", e);
                  }
              }
          }
          return copy;
      }
  
      /**
       * Creates a new timeseries by copying a subset of the data in this time
       * series.
       *
       * @param start  the first time period to copy (<code>null</code> not
       *         permitted).
       * @param end  the last time period to copy (<code>null</code> not
       *         permitted).
       *
       * @return A time series containing a copy of this time series from start
       *         until end.
       *
       * @throws CloneNotSupportedException if there is a cloning problem.
       */
      public TimeSeries createCopy(RegularTimePeriod start, RegularTimePeriod end)
          throws CloneNotSupportedException {
  
          ParamChecks.nullNotPermitted(start, "start");
          ParamChecks.nullNotPermitted(end, "end");
          if (start.compareTo(end) > 0) {
              throw new IllegalArgumentException(
                      "Requires start on or before end.");
          }
          boolean emptyRange = false;
          int startIndex = getIndex(start);
          if (startIndex < 0) {
              startIndex = -(startIndex + 1);
              if (startIndex == this.data.size()) {
                  emptyRange = true;  // start is after last data item
              }
          }
          int endIndex = getIndex(end);
          if (endIndex < 0) {             // end period is not in original series
              endIndex = -(endIndex + 1); // this is first item AFTER end period
              endIndex = endIndex - 1;    // so this is last item BEFORE end
          }
          if ((endIndex < 0)  || (endIndex < startIndex)) {
              emptyRange = true;
          }
          if (emptyRange) {
              TimeSeries copy = (TimeSeries) super.clone();
              copy.data = new java.util.ArrayList<TimeSeriesDataItem>();
              return copy;
          }
          return createCopy(startIndex, endIndex);
      }
  
      /**
       * Tests the series for equality with an arbitrary object.
       *
       * @param obj  the object to test against (<code>null</code> permitted).
       *
       * @return A boolean.
       */
      @Override
      public boolean equals(Object obj) {
          if (obj == this) {
              return true;
          }
          if (!(obj instanceof TimeSeries)) {
              return false;
          }
          TimeSeries that = (TimeSeries) obj;
          if (!ObjectUtilities.equal(getDomainDescription(),
                  that.getDomainDescription())) {
              return false;
          }
          if (!ObjectUtilities.equal(getRangeDescription(),
                  that.getRangeDescription())) {
              return false;
          }
          if (!ObjectUtilities.equal(this.timePeriodClass,
                  that.timePeriodClass)) {
              return false;
          }
          if (getMaximumItemAge() != that.getMaximumItemAge()) {
              return false;
          }
          if (getMaximumItemCount() != that.getMaximumItemCount()) {
              return false;
          }
          int count = getItemCount();
          if (count != that.getItemCount()) {
              return false;
          }
          if (!ObjectUtilities.equal(this.data, that.data)) {
              return false;
          }
          return super.equals(obj);
      }
  
      /**
       * Returns a hash code value for the object.
       *
       * @return The hashcode
       */
      @Override
      public int hashCode() {
          int result = super.hashCode();
          result = 29 * result + (this.domain != null ? this.domain.hashCode()
                  : 0);
          result = 29 * result + (this.range != null ? this.range.hashCode() : 0);
          result = 29 * result + (this.timePeriodClass != null
                  ? this.timePeriodClass.hashCode() : 0);
          // it is too slow to look at every data item, so let's just look at
          // the first, middle and last items...
          int count = getItemCount();
          if (count > 0) {
              TimeSeriesDataItem item = getRawDataItem(0);
              result = 29 * result + item.hashCode();
          }
          if (count > 1) {
              TimeSeriesDataItem item = getRawDataItem(count - 1);
              result = 29 * result + item.hashCode();
          }
          if (count > 2) {
              TimeSeriesDataItem item = getRawDataItem(count / 2);
              result = 29 * result + item.hashCode();
          }
          result = 29 * result + this.maximumItemCount;
          result = 29 * result + (int) this.maximumItemAge;
          return result;
      }
  
      /**
       * Updates the cached values for the minimum and maximum data values.
       *
       * @param item  the item added (<code>null</code> not permitted).
       *
       * @since 1.0.14
       */
      private void updateBoundsForAddedItem(TimeSeriesDataItem item) {
          Number yN = item.getValue();
          if (item.getValue() != null) {
              double y = yN.doubleValue();
              this.minY = minIgnoreNaN(this.minY, y);
              this.maxY = maxIgnoreNaN(this.maxY, y);
          }
      }
  
      /**
       * Updates the cached values for the minimum and maximum data values on
       * the basis that the specified item has just been removed.
       *
       * @param item  the item added (<code>null</code> not permitted).
       *
       * @since 1.0.14
       */
      private void updateBoundsForRemovedItem(TimeSeriesDataItem item) {
          Number yN = item.getValue();
          if (yN != null) {
              double y = yN.doubleValue();
              if (!Double.isNaN(y)) {
                  if (y <= this.minY || y >= this.maxY) {
                      updateMinMaxYByIteration();
                  }
              }
          }
      }
  
      /**
       * Finds the bounds of the x and y values for the series, by iterating
       * through all the data items.
       *
       * @since 1.0.14
       */
      private void updateMinMaxYByIteration() {
          this.minY = Double.NaN;
          this.maxY = Double.NaN;
          for (TimeSeriesDataItem aData : this.data) {
              TimeSeriesDataItem item = aData;
              updateBoundsForAddedItem(item);
          }
      }
  
      /**
       * A function to find the minimum of two values, but ignoring any
       * Double.NaN values.
       *
       * @param a  the first value.
       * @param b  the second value.
       *
       * @return The minimum of the two values.
       */
      private double minIgnoreNaN(double a, double b) {
          if (Double.isNaN(a)) {
              return b;
          }
          if (Double.isNaN(b)) {
              return a;
          }
          return Math.min(a, b);
      }
  
      /**
       * A function to find the maximum of two values, but ignoring any
       * Double.NaN values.
       *
       * @param a  the first value.
       * @param b  the second value.
       *
       * @return The maximum of the two values.
       */
      private double maxIgnoreNaN(double a, double b) {
          if (Double.isNaN(a)) {
              return b;
          }
          if (Double.isNaN(b)) {
              return a;
          }
          else {
              return Math.max(a, b);
          }
      }
  
  }
  